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Assessment of fatigue crack growth resistance of newly developed LTT alloy composition for the repair of high strength steel structures
Get PDFTensile residual stress (TRS) is a well-known factor that deteriorate the integrity of welded joints. Fatigue failure is accelerated by the existence of TRS introduced during the welding process. There have been efforts in the last two decades to develop filler alloys that can reduce TRS by introducing compressive residual stress (CRS) to oppose the TRS in high strength steel welded joints. These works are based on the theory of austenite (γ) to martensite (α’) transformation and the filler is often called a low transformation-temperature (LTT) alloy. Many studies have reported that the fatigue strength (FS) of weld joint made with LTT alloy is many times better than that of the conventional fillers. It is reported to be particularly useful in the repair of high strength steel structures. However, studies on the fatigue crack growth (FCG) behaviour of these LTT alloys is scarce. In this work, we developed Fe-CrNiMo based LTT weld metal composition, assessed its FCG behaviour and compared the results with that of a conventional welding wire (ER70S-6). It is found that ER70S-6 weld metal obtained under relatively fast cooling is extremely tough, but the associated heat affected zone (HAZ) has poor resistance to FCG which obscured the benefit of the tough weld metal. High heat input or condition that results to slow cooling of the ER70S-6 weldment deteriorates its resistance to FCG. Unfortunately, despite its low martensite start temperature of 231±7 and the anticipated beneficial effect of induced CRS, the LTT alloy studied had the lowest FCG resistance. The LTT alloy appears to have an intrinsic microstructural feature or a ‘fault line’ that reduced its resistance to FCG. While the LTT alloy weld metal has poor resistance to FCG, the associated HAZ resisted FCG more than the HAZ associated with ER70S-6 weld metal. It is observed that aligning the ER70S-6 weld metal perpendicular to the crack front produced the highest resistance to fatigue crack initiation and propagation. In the case of ER70S-6, it is believed that the weld metal induced a CRS at the notch tip which resulted to the high fatigue resistance. In the case of the LTT alloy, perpendicular alignment of the weld metal produced slight improvement.This project is funded through EPSRC Doctoral prizeJournal of Advanced Joining Processe
Simulating enhanced vertiport management in a multimodal transportation ecosystem
Get PDFThe advanced air mobility (AAM) industry envisions a transformative transportation ecosystem for passengers and cargo deliveries. Nonetheless, coordinating large volumes of new aerial vehicles necessitates innovative unmanned aircraft system (UAS) traffic management (UTM) solutions, supported by a robust vertiport infrastructure. Moreover, AAM will form part of a broader multimodal ecosystem, posing additional technical, procedural and operational challenges. This work thereby presents a simulation tool in AnyLogic for deploying, training and testing collaborative and intelligent AAM decision-making frameworks within a multimodal transportation system. The platform integrates multiple vertiports with diverse resource constraints, and offers a flexible solution to investigate the impact of different vertiport designs, layouts and procedures. AAM-specific influences are also introduced, including electric vehicle batteries, heterogeneous vehicle specifications, stricter flight envelopes, and hyper-local micro-weather variations. The model further acknowledges the complex inter-dependencies within a multimodal environment to capture fluctuating travel demands and dynamic passenger flows within transportation terminals. This scalable simulation tool thereby enables the development of enhanced vertiport management and AAM traffic coordination solutions, and facilitates exploratory research on multimodal coordination amongst air, ground, rail and sea transportation systems.The research work disclosed in this publication is partially funded by the Malta Tertiary Education Scholarships Scheme, and by Innovate UK under grant agreement No.10023201, as part of the Air Mobility Ecosystem Consortium (AMEC) project.2024 IEEE Aerospace Conferenc
Guest editorial: Climate Neutral Supply Chains
Get PDFThe International Journal of Logistics Managemen
Aspergillus ullungdoensis sp. nov., Penicillium jeongsukae sp. nov., and other fungi from Korea
Get PDFEurotiales fungi are thought to be distributed worldwide but there is a paucity of information about their occurrence on diverse substrates or hosts and at specific localities. Some of the Eurotiales, including Aspergillus and Penicillium species, produce an array of secondary metabolites of use for agricultural, medicinal, and pharmaceutical applications. Here, we carried out a survey of the Eurotiales in Korea, focusing on soil, freshwater, and plants (dried persimmon fruits and seeds of Perilla frutescens, known commonly as shiso). We obtained 11 species that—based on morphology, physiology, and multi-locus (ITS, BenA, CaM, and RPB2) phylogenetic analyses—include two new species, Aspergillus ullungdoensis sp. nov. and Penicillium jeongsukae sp. nov., and nine species that were known, but previously not described in Korea, Aspergillus aculeatinus, Aspergillus aurantiacoflavus, Aspergillus croceiaffinis, Aspergillus pseudoviridinutans, Aspergillus uvarum, Penicillium ferraniaense, Penicillium glaucoroseum, Penicillium sajarovii, and one, Penicillium charlesii, that was isolated from previously unknown host, woodlouse (Porcellio scaber). We believe that biodiversity surveys and identifying new species can contribute to set a baseline for future changes in the context of humanitarian crises such as climate change.Fungal Biolog
Modifications in gene expression and phenolic compounds content by methyl jasmonate and fungal elicitors in Ficus carica. Cv. Siah hairy root cultures
Get PDFBackground :
One of the most effective strategies to increase phytochemicals production in plant cultures is elicitation. In the present study, we studied the effect of abiotic and biotic elicitors on the growth, key biosynthetic genes expression, antioxidant capacity, and phenolic compounds content in Rhizobium (Agrobacterium) rhizogenes-induced hairy roots cultures of Ficus carica cv. Siah.
Methods :
The elicitors included methyl jasmonate (MeJA) as abiotic elicitor, culture filtrate and cell extract of fungus Piriformospora indica as biotic elicitors were prepared to use. The cultures of F. carica hairy roots were exposed to elicitores at different time points. After elicitation treatments, hairy roots were collected, and evaluated for growth index, total phenolic (TPC) and flavonoids (TFC) content, antioxidant activity (2,2-diphenyl-1-picrylhydrazyl, DPPH and ferric ion reducing antioxidant power, FRAP assays), expression level of key phenolic/flavonoid biosynthesis genes, and high-performance liquid chromatography (HPLC) analysis of some main phenolic compounds in comparison to control.
Results :
Elicitation positively or negatively affected the growth, content of phenolic/flavonoid compounds and DPPH and FRAP antioxidant activities of hairy roots cultures in depending of elicitor concentration and exposure time. The maximum expression level of chalcone synthase (CHS: 55.1), flavonoid 3′-hydroxylase (F3’H: 34.33) genes and transcription factors MYB3 (32.22), Basic helix-loop-helix (bHLH: 45.73) was induced by MeJA elicitation, whereas the maximum expression level of phenylalanine ammonia-lyase (PAL: 26.72) and UDP-glucose flavonoid 3-O-glucosyltransferase (UFGT: 27.57) genes was obtained after P. indica culture filtrate elicitation. The P. indica elicitation also caused greatest increase in the content of gallic acid (5848 µg/g), caffeic acid (508.2 µg/g), rutin (43.5 µg/g), quercetin (341 µg/g), and apigenin (1167 µg/g) phenolic compounds.
Conclusions :
This study support that elicitation of F. carica cv. Siah hairy roots can be considered as an effective biotechnological method for improved phenolic/flavonoid compounds production, and of course this approach requires further research.BMC Plant Biolog
Investigation of wind turbine static yaw error based on utility-scale controlled experiments
Get PDFWind energy represents a promising alternative to replace traditional fossil-based energy sources. For this reason, increasing the efficiency in the conversion process from wind to electrical energy is crucial. Unfortunately, the presence of systematic errors (mostly related to the yaw and pitch angles) is one of the key factors causing underperformance, and for this reason, it requires adequate identification. The present work deals with diagnosing wind turbine static yaw error, occurring when the wind vane sensor is incorrectly aligned with the rotor shaft. A thorough investigation methodology is proposed by considering a unique experimental test-up shared by the Eolos Wind Research Station. A utility-scale wind turbine has been imposed to operate subjected to several static yaw errors and reference meteorological data collected nearby the wind turbine were available. By analyzing the relation between the meteorological data and the SCADA data collected by the wind turbine, a systematic alteration in the measurements of nacelle wind speed in the presence of the yaw error is explicitly shown. This phenomenon has been overlooked in the literature and leads to revisiting the methods mostly employed for the diagnosis of the error. Furthermore, a correlation between the presence of static error, increased blade pitch, and heightened levels of tower vibration is observed. In summary, this work provides a comprehensive characterization of the experimental evidence associated with the presence of a wind turbine static yaw error. This paves the way for more effective diagnostic techniques for wind turbine yaw errors, potentially revolutionizing data-driven maintenance strategies.IEEE Transactions on Industry Application
Assessing metal extraction from metalliferous waste: A study using deep eutectic solvents and chelating agents vs. ethylenediaminetetraacetic acid
Get PDFConventional methods of metal recovery involving solvents have raised environmental concerns. To address these concerns and promote sustainable resource recovery, we explored the use of deep eutectic solvents (DES) and chelating agents (CA) as more environmentally friendly alternatives. Goethite and blast oxide slag dust (BOS-D) from heap piles at their respective sites and characterised via ICP-MS. The greatest extraction of critical metals was from goethite, removing 38% of all metals compared to 21% from the blast oxide slag. Among the tested CA, nitrilotriacetic acid (NTA) was the most effective, while for DES, choline chloride ethylene glycol (ChCl-EG) demonstrated superior performance in extracting metals from both blast oxide slag dust and goethite. The study further highlighted the selectivity for transition metals and metalloids was influenced by the carboxyl groups of DES. Alkaline metals and rare earth lanthanides extractions were favoured with DES due to improved mass transfer and increased denticity, respectively. In comparison to ethylenediaminetetraacetic acid (EDTA), typically used for metal extraction, CA and DES showed comparable extraction efficiency for Fe, Cu, Pb, Li, Al, Mn, and Ni. Using these greener chelators and solvents for metal extraction show significant promise in enhancing the sustainability of solvometallurgy. Additional conditions e.g., temperature and agitation combined with a cascading leaching process could further enhance metal extraction potential.This research was funded by the European Regional Development Fund as part of the Interreg Northwest Europe project “Regeneration of past metallurgical sites and deposits through innovative circularity for raw materials” (REGENERATIS) (NWE918).Journal of Environmental Managemen
Potential for energy recovery from boundary-layer ingesting actuator disk propulsion
Get PDFThe theoretical benefits of highly integrated propulsion systems are highlighted herein by assessing the potential for energy recovery utilization using actuator disk propulsion. Decomposing aerodynamic forces into thrust and drag for closely integrated bodies, particularly those employing boundary-layer ingestion, becomes challenging. In this work, a mechanical energy-based approach was taken using the power balance method. This allowed the performance to be analyzed through the mechanical flow power in the fluid domain, disregarding the need for any explicit definition of thrust and drag. Through this, the benefit of boundary-layer ingestion was observed from a wake energy perspective as a decrease in the downstream mechanical energy deposition and associated viscous dissipation. From a propulsion perspective, the reduction in power demand necessary to produce propulsive force indicated the possibility of power savings by utilizing the energy contained within the ingested boundary-layer flow.Journal of Aircraf
Calibration and testing strategies to correct atmospheric effects on star tracking algorithms
Get PDFStar trackers are usually considered to be the most accurate sensors, able to achieve a sub-arcminute precision. Star tracker algorithms are often tested and validated with simulated space views. Testing the algorithms with real space images is expensive as it requires implementing them on existing in-space star trackers, or to launch new satellites. This study shows that those algorithms are usually performing poorly with ground-based sky pictures and that some adaptations are necessary to take into account the atmospheric effects. The adaptation of star tracking algorithms to ground pictures could ease the prototyping phase for new star trackers, or for ground-based and air-borne star trackers, without the need to buy specific testing simulators. In order to tackle this issue, this study will start by implementing and testing two published Lost-In-Space algorithms with a simulated sensor to compare their performance against various noise sources. After comparing the space-based generated views with ground-based images, an adaptation for the aforementioned algorithms is proposed. In order to counter the effect of atmospheric extinction, the number of stars visible in the image is increased by modifying the field-of-view of the camera, the exposure time and estimating the experimental inter-star angular distance error. The idea is to match the star density used in the state-of-the-art algorithms in the experimental pictures. The modified algorithms are tested with the experimental images, and the adaptation process is validated with a good success rate.Astronomy and Computin
Seeding-free inlet flow distortion measurements using filtered Rayleigh scattering: integration in a complex intake test facility
Get PDFHighly integrated propulsion systems to achieve fuel savings and reduction of emissions in future aircrafts call for new measurement methods to assess inlet conditions at the engine fan face. Propulsion systems are expected to operate at higher levels of total pressure, total temperature, and swirl distortion due to flow interaction with aerodynamic surfaces and inherent flow distortion within convoluted intakes. Filtered Rayleigh Scattering (FRS) offers capability to assess all these quantities at once, and without the need of seeding particles which cannot be used for in-flight measurements. This paper aims at increasing the technology readiness level of this measurement technique through the application on a lab-scale S-duct diffuser tests and benchmark against Stereo-Particle Image Velocimetry (S-PIV) measurements. Methods to improve the optical integration and mitigate the effect of varying background conditions are hereby explored. Overall, this represents a step forward in the use of FRS as a turnkey solution for the testing and development phase of future propulsion systems.AIAA SCITECH 2024 Foru